Battery cell voltage comparison system



May 8, 1956 J. GRILLO BATTERY CELL VOLTAGE COMPARISON SYSTEM 2 Sheets-Sheet l Filed July 24,l 1952 nu hb Nb /ITTORNEY May 8, 1956 J. GRILLO 2,745,090

BATTERY CELL VOLTAGE COMPARISON SYSTEM Filed July 24, 1952 2 Sheets-Sheet 2 ATTORNEY United States Patef j 2,745,090 BATTERY CELL VOLTAGE COMPARISON sYsrEM Joseph Grillo,New York, N. Y., assgnor to Ward Leonlard Electric Company, a corporation of New York Application July 24, 1952, Serial No. 300,686 is Claims. `(cl. 340-253) i"Iliis.invention relates to electrical systems, and is applicable particularly to the indication by a single means of'. the condition of any one of a plurality of electrical devices in relation to a standard. This invention is useful with electrical devices such as batteries, thermocouples,

etc.

y In various instances, .wherein a group or bank of batteries are used, it is often desirable to have a continuous check of the voltage of each battery. In certain types of equipment, the operating voltage of all the batteries should be above a permissible minimum voltage. When a battery drops to this voltage, it is desirable to have an immediate indication of'this condition. The departure of'a battery from the Operating range may require a discontinuance or a reduction of the current drain. This is particularly true in the case of submarine batteries, where any battery that becomes fully discharged absorbs energy, so that it is likely to reverse its polarity and create dangerous conditions. These batteries should not fall below a predetermined minimum voltage. This should be above the voltage'of a fully discharged cell so that sufiicent warning is given to permit the reduction of the current drain on the batteries or a recharging of the battery. It is preferable to indicate the dropping of the cell= voltage by a single indicating means. The indicating means or lamp would be located at a main panel in view of the operating personnel. This would provide a continuous indication of the condition of the batteries and would lighta signal when a battery was below the required Voltage. l

f An object of this invention is to provide an electrical system with an indicating means that is sensitive to a change in the relationship of an electrical device to a given standard.

Another object of 'the invention is to provide an electrical system that continuously and separately monitors each current or voltage source of a group of sources.

Another object of the invention is to providean electrical circuit that continually checks the voltage of a single cell of a group of cells and automatically and instantaneously indicates when the voltage of a cell drops below a permissible minimum.

' Another Vobject of the invention is to provide a voltage monitoring system that has a general indication and a specic indication of a low voltage cell.

Other and further objects and advantages of the invention will be apparent from the following description, taken in connection with the accompanying drawings, in which Fig. l is a diagrammatic illustration of a typical system; and f Fig. 2 is a schematic diagram of the system.

In the case of banks of batteries, it is desirable to operate each cell at or above a given minimum voltage, determined by various operating criteria not discussed herein. This minimum operating voltage isbetween a .maximum operating voltage of a fully charged cell and a minimum operating voltage of a discharged oell. The

value of these voltages decreases the load curr'entfinl ice creases. l As the loadcurrent increases the voltage of the cell proportionally` decreases. A given oper;I

ating voltage may. be from 1.74 volts for" zero `current drain to 1.47 volts `for full load current. Under a current drain, `the voltage of each cell is preferably kept above this given voltage limit. If a cell drops to this limit, the batteries may be recharged, or, if continued use ot the batteries is required, the current drain may be reduced. The `particular purpose of this embodiment is to provide an indication when any one of the cellsldrops,

. voltage, the output of the magnetic amplitierincreases j to criticalchanges in the voltages of the cells.

greatly and the lamps light.

Tl-1ere are 252 cell amplifiers, 11-1 to 11252, veach connected across the terminals of cells C-1 to C-252 respectively. ,The outputs of the cell amplifiers respond the voltage'of a particular cell drops below a permissible' minimumrvoltage, the output current of the cell increases and lightsthe individual indicating lamp 24 and the gen. eral indicating lamp 25. The general vindicating lamp is` connected to the outputs of the cell amplifiers 11 by means lof the first stage mixers 27, second stage mixers 28, third stage mixer 29 and the reactor 74.

.The cell amplifiers 11-1 to 11-252 areconnected in groups of seven to the mixers 27-1 to 27f36. In Fig. 1 the rst group of seven cell amplifiers 11-1 to 11-7 are shownconnected to mixer 27-1. The mixers 27-1to 27-36are in turn connected in groups of six tothe second stage mixers 28-1 to'28-6. The mixers 28-1 to 28-6 are connected to the last or third stage mixer 29.

The-output current' of each magnetic amplifier 11 is controlled by a' comparison of the llux of the current from the respectivecell and the ilux of the referencecurrent from the reference circuit 12. The Output ofy the cellamplifer remains at a negligible value until the current from thecell drops in relation to the currentfrom the-reference circuit. When this critical relation occurs, afurther' reduction causes the output of the cell amplifiers to increase from a negligible value to a substantialvalue. 'The increased output raises theloutput lin the successive mixers and lights the lamp 25. The bias winding 21 and the control winding 22 of the cell amplifier create ,opposingy uxes in the respective cores. The bias windingfux is additive to the llux of the anode windings and the ux of the control winding opposes the flux of the anode winding.v l

The reference circuit 12 provides a current that'varies proportionally with lthe changes of the cell voltage du'e to load current so that the standard set by the reference circuit will correspond to the predetermined operating limit. yThe reference current is supplied to the bias windings 21 of the magnetic amplifiers 11. The bias windings 21 of the group of magnetic amplifiers 117-1 to 11-7 are connected in series with the bias windings of the group of amplifiers 11-8 to 11-14 to form a bias circuit loop. There are eighteen of these loops supplied with current bythe reference circuit.

The magnetic amplifiers 11 comprise two saturable reactOrs11a,'11b of the toroidal type. 18a, 18b are wound on lthe cores of the reactors 11a, v11b respectively'and are connected inseries with the rectiers 31a, 31b respectively to provide an alternating output current from the magnetic amplifier 11. The feedback windings 33a, 33b are separately wound on the respective cores and are connectedl in series with each other and the anode windings 18a, 18b. The individual indicator lamps are connected in series with theanode circuit, and pass the.

Patented May 8,

When

- similarly connected to a mixer.

current through the anode windings. By-pass resistors 23-11023-32 are connected'in parallel with"lamps'24"1 to 24-252 to provide a secondfpassage for the anode current, Aso that, if `a lamp Z4 fails, the general indicator lainp125 will still light.

'The currents'in the control winding .andthe'bias ,winding areA set'at such a value that voltages of' thecell above the set minimum will render the reactors'lla, 'Hjb -unsaturated. The flux of the'biaswinding saturates the ,reactors while theiiux of the ncontrol-winding opposes and cancels theux of the bias winding to rende'rthe reactors-unsaturated, as'long as 'the cellvo'ltage-isabovethe setminimum. -The-valueof the control current at which the reactors shift'irornl unsaturatedfto Vsaturated isset -by the "adjustmentof the rheostat 12S-and vthe voltage drop of the shunt 35. This-shift-lfrom-unsaturatedto saturated condition is setftofoccur when -the cell voltage reaches the `desired minimum value. The -rheostat 43 determines the-minimum operating level and the shunt 35' varies the iiux 'of--the 'bias winding with the changes in the load current. The anode current througlrthe ffeedback windings`f33a, E53-b creates a iiux additive to the flux of Vthe anode windings 18a, 13b respectively. `The feedback windings increase the slope of the saturation curve of the'rreactors 111a,'11b softhat a slight chan-ge in the control y setsorthat a change lof 25 millivolts in thefcell'voltage` at-thev minimum limit will cause the-necessary flux-change.

Thegroup of amplifiers `ll-ithrough 11-7 have-their outputs connected to the mixer'2'7.-1, and the group of amplifiers 11-8 to 1l-14 have their outputs connected tofthefmixer 274. The other groups of amplifiers are Each of the outputs of thevamplifiers is connected directly to thecontrol winding ofthe`-respective lmixers so that each amplifier vdelivers current tothe control winding without finterferingwith the otheramplifiers of the same group.

fT-hefiirst mixerstage comprises thirty-six magnetic arnpliers. Each `amplifier comprises two toroidal type saturablefreactorsA-l, 62 with anode windings 61a, 62a respec'tively. The bias winding 6111, 62h are connectedin series-with resistor 32 across a bias supply which consistslof a rectifier 50,-adjusting resistor V51, and `lter capaeitorfSS, and provides a ux .that -holds the loutput currentofthe-mixer to a zero ora negligible lvalue Ywhen therefis nosignal impressed onthe control windings'lc and62c. 'The control windings are `connected in series, and receivefthe output current `from-thevamplifiersl 11. Theioutput currentvpasses alternately through-the-anode windings 61a and vrectifier 63 in series and the anode winding 62a-and -rectier64 in series. Thus ankalternating-'current .is impressed on the succeeding Lmixerstage.

Thesecondstage mixers lare similar to theiirstzstage mixers and each comprise two saturablereactors-65,66 Of-ft-he toroidal type .with yanode lwindings '65a,:-66a,'-bias windingsV 6511, oub, andcontrolwindingsSc, 66c. "The control zwindingslc, y66C of each mixer are connectedl to the outputs of'a group of :six first Stagemixersfand receivean-alternating currentftherefrom. `Aslong asthe output currents of `the preceding mixers -of -lthe -group are-negligible the bias windings 65b, 66bt maintain the output current of the anodewindings xatan inetfective value. The anode windings 6541, ,6619 ,supply inalternating output current through the rectifiers 67, 68, to the thirder last stagemixer 29. hcsbi. Kers ofthe secondl stage are eachl connected to them er`29. lAll thesignals from. theampliersll pass throughthisdast stage. The mixer 29 also has twosaturable reactors '10, 7;1\.wit h anode windings'tlz, 71a,l and, control .winding1'70c, 71e. The bias windings 7llb,'7 1lb are supplied with c urrentffrom'the bias rectiiierS througlig,` resistor @84 toihold the outputto-a value that doesvAnot-cause `therlanjlp ceding mixers, and, on application of a signal, the alternating output currentin the anode windings 70a, "71a and the rectiiicrs 69, 73 in series respectively increases. The rectifier 72 rectiiies this alternating output and impresses a direct current on the control winding 74C of the reactor 74 that lowers the impedance of the reactor and increases the currentthroughthe windings 74a, 74b.

, The windings 74a, 74b are in series with each other and Qffsatureblerreacters 4.?. @monagence thelamp 25, and are :supplied with current-fromthitransformer winding 40.

The bias windings cfs-ash Stage .are Supplied circuit 38 and a `corripensating circuit 39. "The 'l'evel adjustment circuit comprises a rectifier 44 rectifying the alternating current -from the -secondary winding 19b au adjusting rheostat 43, a dropping resistor fili-and iilter reactoril, and provides an operating current'level.' The compensating circuit 12 includes the shunt 35 to provide a vcurrent-which varieswith changes in the load'current.

The level-adjustment current-and-the compensating ,cur-y rentaarecombined inthe-first stage ofthe'referene circuit 12 v4to controlthereference currentinaccordance with the amount ofA loadcurrent. andthe-desired operating level. `The first 4stage-comprises -a-pair of `saturable-reactors'; 37'having Y anode windings 36a, 37171,*` bias-windings 36b, 57h, -control=windings 36C, l37e land feedback windiugsf, 371. fTheoperatinglevel adjustment'circuit and the compensatingcircuit are connectedto the-bias windings -and control windings respectively. Tihel-bias windings arefconnected lin .serieswithleach.other :and also in. seriesJwith-,the rheostat 43, .and choke 41-. :The output. of rectifier .-44 isx connected .acrossithefbias wind,- ings, theirheostatnandthenchoke .41. vThe -rheostat 43vsets @the minimtunioperatinglevel ofwthe. cells. J'The controlwindings'ic,'137cf.areconnected in series across the .-shunt;35-f,and.-;the. current. through` `the control wirrdf ings'varies the outputcurrentwith the changesin load current. 'The anodeiwindiugsfa, 37a .are,conneeted;in Series fwthfrectiers 153., ,544 respectivelyto-.provide yan alternating-output current- Ehe-rectierf-SZ.reetiesfrhis outputiandirresents -afislirectgcurrent toghe second .stage magnetic amplifier. The second stage comprises,a,pair .ings A811, iilafbiaswindiugsfb 42h-and w1ifwiilsinizsi 8 42c- Tihe ,terrific @angered.togtlisontrel ings 48e, 49e in series, and impresses a direct curren on the Avzviuliussthat -eQutrfQls the.utnur.orrefrsn9 ,r-

' rent.

2.5toflight'undervnofsignalnconditions. The controliwindl The .hiss windings-fhrend flQb-.aresrnsetsdf t0 is@ bias renin S0 ,audaci fthesecgnd. stages-@asias t 4th proper AQueralt grange .The amide windings LAQ? are supplied. with alteipatingzurrgntfrqm the .transfgtmsf @sudare:infectiesw rectiiersw 5.7- ,"Ehergutmlt current is rectified by the rectifier .158,.5is filteredi'bygeactQrfgS .andsapactoril and -imprssssd @rutile-sieh??? bias.circuitsoffempl 11. @Se @irren Curr L '1&9- SiStOrS 15 are Calibliauusfrssstgrs in ,snesiivith-1thel cellvainplisr :biastsirsuits -,Ihe,vo1tase across theyre- Ssters .i determine hewalue.ofnthereference current. 'ftlhenyohage.;across;the bias circuitsnis` fedubackto the-.feedback windings 361, 37f of the first stage through compensating network 46. .'lhisafeedbaclc ,increasesfathe flinearityot ;the referencecircuit andiitsi accuracy of operation. The compensatingguetwork 4.6 fis. connected. in-ithef-feedback.circuitsandrrcrides Ate.rv-..stabilitvs-.Qf Qperationpf heiratetence irc it.

@Tfhetimgffthe resistanceiotiresistorsflandi lnwhish have negligible. temperature continents,..- @resistirse of the windings in series with them is kept constant, so that the operating level does not shift with temperature. Although this embodiment has `been described in connection with battery cells it also can be readily adapted to indicate the electrical condition of other current or voltage devices such as thermocouples or the like. The amplifiers 11 could be connected to a plurality of thermocouples located at spaced points or at a central location. The current from the thermocouple actuates the amplifier and causes an indication at the lamps 24, 25. The rheostat 43 would set the range of operation of the thermocouple, depending on the circuit arrangements. The shunt 35 would be dispensed with. y

Although a particular embodiment of the invention has been described, various modifications and various applications of the invention may be made without departing from the scope thereof.

I claim:

1. An electrical system for monitoring a plurality of electrical devices comprising a plurality of separate magnetic amplifiers each directly connected to a different electrical device to receive a monitoring current from a respective electrical device, a reference circuit directly connected to each of said magnetic amplifiers and providing a reference current on comparison' with said monitoring current in said magnetic amplifiers producing a ux differential maintaining a non-activating output on an approved relationship producing an activating output on occurrence of a predetermined unapproved krelation between said currents, a set of mixer amplifiers with each mixer amplifier connected to a separate group of said magnetic amplifiers, a second set of mixer amplifiers with,` each second mixer amplifier connected to a separate group of said first mixer amplifiers, said first and second mixers combining the outputs of said magnetic amplifiers for actuation of a general indicator on occurrence of the predetermined relationship in any magnetic amplifier.

2. An electrical system for monitoring each cell voltage of a plurality of cells connected in series comprising a plurality of saturable reactors each havinga control winding, a bias winding andanode winding, means for connecting each control winding across a respective cell to receive a monitoring current directly therefrom to cre.

ate a flux in said respective reactor proportional to the cell voltage said bias windings connected in series, a reference circuit having an output connected across said series connected bias windings to supply a bias current varying inversely to the output load current of the cells, said bias windings creating a liux in opposition to the flux of the control winding so that when the control voltage drops below a critical voltage the impedance of the anode windings is sharply reduced and the output current in-v creases for actuating an indication means.

3. An electrical system as described in claim 2 wherein said saturable reactor has a feedback winding connected in series with the anode winding to increase the slope of the saturation curve so that a small change in the cell voltage at the critical voltage will reduce the impedance 'of the anode windings.

4. An electrical system as described in claim 2 wherein said reference circuit has a saturable reactor with anode windings, a control winding and a bias winding, said control winding adapted to be connected in parallel to one of the output lines of the cells to receive a small portion of the output current, said small portion of the output current creating a flux in opposition to the flux of the anode winding, said bias winding adapted to be supplied with a direct current, and a rheostat connected in series with said bias winding to set the reactor in the desired operating range.

5. A voltage monitoring system for providing a constant check of each cell voltage of a group of cells comprising a separate reference circuit connected to one of the output lines of the cells to vary the output current of said circuit inversely to the output current of the group of cells, a group of saturable reactors corresponding to the group of cells each saturable reactor having a bias winding, a control winding and an anode winding, said control winding connected across the cell to impress a voltage on the winding and create a flux to increase the impedance of the anode winding, said bias winding supplied with current from said output of the reference circuit to provide a current opposing said control flux and decreasing the impedance of the anode winding, means for connecting said saturable reactors in groups including means for connecting the anode windings of a group in parallel, mixers of a first stage having the outputs connected in parallel, second stage mixers each connected to the parallel outputs of a group, said second stage mixers having outputs connected in parallel to combine the outputs of the preceding mixers, a third stage mixer con References Cited in the le of this patent UNITED STATES PATENTS 2,547,011 Jacobsen Apr. 3, 1951 2,613,248 Christie Oct. 7, 1952 2,640,098

Grillo May 26, 1953 

